#include<stdio.h>
#include<math.h>
int main (){

    double c1,c2;
    scanf("%lf%lf",&c1,&c2);
    const double CLKTCK=100;
    int p = int(round((c2-c1)/CLKTCK));
    int hour=0,min=0,sec=0;
    while (p!=0){
        sec++;
        if(sec==60){
            min++;
            sec = 0;
        }
        if (min==60){
            hour++;
            min=0;
        }
        p--;
    }
    printf("%02d:%02d:%02d\n",hour,min,sec);
    return 0;
}
// 秒转化为分钟小时，可以不采用模拟而采用除法 p/3600 p%3600/60 p%60
// %02d %2d